The present disclosure relates generally to thermoplastic packages or bags that are triple-folded and sealed by hot air to provide resistance to insect infestation and methods for making such packages or bags.
Product packaging is important with respect to the storage of the product contained therein. Packages that are easy to open and enable a consumer to easily access a product contained in the package are particularly popular. However, the packaging should also be tightly sealed to help maintain the freshness of the product stored in the packaging, especially with products such as comestible products or food products for which product freshness and consistency is highly desirable.
Polywoven bags can be manufactured that exhibit excellent tensile strength qualities making them very suitable for containing a wide variety of materials. However, many closures of polywoven bags form holes in the bag that can allow insects and their larvae to enter the bag.
Grain-based insects are separated into two categories, penetrators and invaders. Invaders are insects that typically have weakly developed mouth-parts at both the larval and adult stages. The invaders, such as Indian meal moths and red flour beetles, account for more than 75% of the infestations of polywoven bags. Invaders commonly enter packages through openings resulting from mechanical damage, defective seals, or holes made by other insects penetrating the package. The newly hatched larvae of invaders typically cause the most damage because they are able to fit through holes as small as 0.1 mm wide.
Most infestations are the result of invasion through seams and closures, and rarely through penetrations. For example, the adult saw-toothed grain beetle has been shown to enter packaging through openings less than 1 mm in diameter, and the adult red flour beetle can enter holes in packaging that are less than 1.35 mm in diameter. Many insects prefer to lay eggs in tight spaces, such as those formed when bags are folded to create closures. These refuges provide a safe place to lay eggs and also give the newly hatched larvae an ideal location to invade the packages.
Insects will take advantage of any sort of opening in a packaging material in order to gain entry. These openings may form as a result of rips, tears, or poor seals or as punctures resulting from normal wear and tear throughout the handling process. Openings in packaging may also be made deliberately in the form of “vents” which allow pressure equalization and air escapement deflation. These vents allow creation of a stable pallet and avoid the bursting or shrinking of the bag during shipment over changing altitudes. However, when an insect “smells” food, the insect will try to reach it. The vent holes are made to reduce bursting and provide a means for air deflation palletizing but they also allow odors to escape, attracting insects and providing an access point for entry.